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51.
Aminomethylphosphonic acid and glyphosate adsorption onto goethite: a comparative study 总被引:3,自引:0,他引:3
Glyphosate is a non-selective, broad spectrum, post-emergent herbicide widely used in weed control. Aminomethylphosphonic acid (AMPA) is one of the main products of biodegradation of glyphosate in natural systems before its ultimate mineralization and also the breakdown product of more complex phosphonates such as nitrilotris-(methylenephosphonic acid). The adsorption isotherms and surface coverage of AMPA and glyphosate (N-phosphomethylglycine, PMG) in aqueous suspensions of goethite as a function of pH were measured. Electrophoretic mobility curves forthe PMG/goethite system were also determined. The ATR-FTIR interfacial spectra of the surface complexes of AMPA and PMG onto goethite were analyzed as a function of the pH and the surface coverage. The phosphonate moiety of these two ligands coordinates to the iron oxide surface with similar structures as the methylphosphonic acid despite the presence of the amino and/or carboxylate groups of their molecules. Two predominating complexes have been identified where the phosphonate group in PMG or AMPA bonds monodentately or bridges bidentately to the surface of iron oxide in an inner sphere mode, while the carboxylate and amino group are noncoordinated to the surface. The stability constants of the surface complexes (triple bond)FeO-P(O)(OH)--R, (triple bond)FeO--P(O)2--R, and ((triple bond)FeO)2--P(O)--R were calculated using the constant capacitance model. 相似文献
52.
Effects of source of gossypol and supplemental iron on plasma gossypol in Holstein steers 总被引:2,自引:0,他引:2
Four experiments were conducted to evaluate factors influencing concentrations of plasma total gossypol (TG) in 30 Holstein steers fed cottonseed products. At the end of each 28-d experiment, steers were weighed and blood samples were collected and analyzed for plasma TG concentrations. During the entire study, steers did not show any overt signs of gossypol toxicity. In the 28 d before experiment 1, 30 steers with a body weight (BW) of 273 kg were fed a standardization diet with 15.0% Upland whole cottonseed (WCS) that resulted in a mean intake of 9.08 g/d of TG per steer/d and a plasma TG of 1.66 μg/mL. In experiment 1, 30 steers were fed 1 of 5 diets with 15.0% Upland WCS, but different levels of supplemental Fe [0, 150, 300, 450, and 600 mg/kg of diet dry matter (DM)]. Average daily gain was not affected by level of Fe in the diet, but DM intake, plasma TG, and plasma TG response decreased linearly as Fe in diets increased. In experiment 2, steers were fed diets with 15.0% Upland cottonseed as whole, cracked, roasted, cracked-roasted, or extruded. Analysis of the seed revealed that roasting or extrusion markedly reduced free gossypol (FG) content. Minor effects on animal performance were observed, but plasma TG decreased with roasting or extrusion of seeds, with the greatest reduction when the seed was cracked and then roasted. In experiment 3, steers were fed 2 levels of WCS (7.0 or 14.0% of DM) with 3 levels of cottonseed meal (2.8, 5.5, or 8.5% of DM) in the diet. Animal performance was not altered by diet, but plasma gossypol concentrations and responses were greater in steers fed diets with more WCS, because of the greater FG intake. In experiment 4, 24 steers were fed diets with 15.0% cottonseed (Upland or Pima) either as whole or cracked. Pima cottonseed increased TG and FG intakes, which resulted in greater plasma TG concentration and response. Animal response to processing of cottonseed tended to differ according to type of cottonseed. However, feeding Pima and cracking of cottonseed increased gossypol availability and plasma TG concentrations. 相似文献
53.
Pentachlorophenol removal from aqueous matrices by sorption with almond shell residues 总被引:2,自引:0,他引:2
Sorption with activated carbon has been the technique preferred for pentachlorophenol (PCP) removal from contaminated waters, but regeneration needs and high operation costs are supporting a renewed interest in the search for alternative sorbents. Among them, almond shell, an agricultural by-product, provides interesting economical advantages, once shells account for 50% (in mass) of the whole almond. In this work, the capacity of almond shells to remove PCP from waters without previous activation was studied in batch conditions. While PCP analysis was performed solid-phase microextraction (SPME) followed by gas chromatography with electron capture detection (GC-ECD), mercury porosimetry and Fourier transform infrared spectroscopy (FTIR) provided a preliminary physical and chemical characterization of the sorbent. Almond shells were essentially a macroporous material, with an average surface area of 12.9+/-2.8 m2/g. The efficiency of PCP removal was 93+/-14%, in 24 h, with an initial concentration of 100 microg/l PCP and 5 microg PCP/g shell. Isotherm data adjusted better to Freundlich equation, where K(F) and 1/n were 0.075+/-0.081 mg(1-1/n) l(1/n) and 1.882+/-0.289, respectively. Average desorption efficiency was 7%, indicating strong adsorption capacity. Results proved that almond shells may be an excellent low-cost alternative for PCP removal from contaminated waters. 相似文献
54.
Our objectives were to compare reproductive responses of dairy cows receiving timed artificial insemination (AI) either at 48 or 72 h after induction of luteolysis and supplemented or not with estradiol cypionate (ECP). Holstein cows (971) had their estrous cycles presynchronized with injections of PGF2α at 37 and 51 d in milk (DIM) and then received an injection of GnRH at 64 DIM and an injection of PGF2α at 71 DIM. Cows were then assigned to a 2 × 2 factorial randomized block experiment; cows in the CoSynch 48 h (CoS48) received a final injection of GnRH concurrent with timed AI 48 h after PGF2α, whereas cows in the CoSynch 72 h (CoS72) received GnRH and timed AI 72 h after PGF2α. Half of the cows in each CoSynch protocol received an injection of 1 mg of ECP 24 h after PGF2α. Therefore, the 4 treatments were as follows: CoS48-NECP (n = 240), CoS72-NECP (n = 246), CoS48-ECP (n = 245), and CoS72-ECP (n = 240). Blood was sampled at 7 d before and at the first GnRH of the CoSynch from all cows for analysis of progesterone concentration in plasma. Cows were classified as anovular when progesterone was less than 1.0 ng/mL in both samples. Blood was also sampled during proestrus from a subset of 123 cows to measure concentrations of estradiol and at 7 d after timed AI to measure concentrations of progesterone. Ovaries from the same subset of 123 cows were examined by ultrasonography to determine ovulatory follicle diameter and incidence of ovulation. Pregnancy was diagnosed at 40 and 68 d after AI. Prevalence of cyclic cows was 72.4% and was similar among treatments. Concentrations of estradiol increased after ECP treatment and at 72 h of proestrus with CoS72. Pregnancy at 40 and 68 d after AI and pregnancy loss were not affected by timing of AI or supplemental ECP. Delaying timed AI to 72 h and supplementation with ECP increased the proportion of cows displaying estrus at AI, and cows detected in estrus had increased pregnancy per AI associated with improved ovulation and increased postovulatory progesterone concentration. These results indicate that extending the proestrus by delaying timed AI from 48 to 72 h plus supplemental ECP, despite increased expression of estrus at timed AI, did not improve reproductive performance of lactating dairy cows at first AI. 相似文献
55.
A study of Lusitano mare lactation curve with Wood's model 总被引:1,自引:0,他引:1
Milk yield and composition data from 7 nursing Lusitano mares (450 to 580 kg of body weight and 2 to 9 parities) were used in this study (5 measurements per mare for milk yield and 8 measurements for composition). Wood's lactation model was used to describe milk fat, protein, and lactose lactation curves. Mean values for the concentration of major milk components across the lactation period (180 d) were 5.9 g/kg of fat, 18.4 g/kg of protein, and 60.8 g/kg of lactose. Milk fat and protein (g/kg) decreased and lactose (g/kg) increased during the 180 d of lactation. Curves for milk protein and lactose yields (g) were similar in shape to the milk yield curve; protein yield peaked at 307 g on d 10 and lactose peaked at 816 g on d 45. The fat (g) curve was different in shape compared with milk, protein, and lactose yields. Total production of the major milk constituents throughout the 180 d of lactation was estimated to be 12.0, 36.1, and 124 kg for fat, protein, and lactose, respectively. The algebraic model fitted by a nonlinear regression procedure to the data resulted in reasonable prediction curves for milk yield ( of 0.89) and the major constituents ( ranged from 0.89 to 0.95). The lactation curves of major milk constituents in Lusitano mares were similar, both in shape and values, to those found in other horse breeds. The established curves facilitate the estimation of milk yield and variation of milk constituents at different stages of lactation for both nursing and dairy mares, providing important information relative to weaning time and foal supplementation. 相似文献
56.
Effect of breeding protocols and reproductive tract score on reproductive performance of dairy heifers and economic outcome of breeding programs 总被引:1,自引:0,他引:1
Stevenson JL Rodrigues JA Braga FA Bitente S Dalton JC Santos JE Chebel RC 《Journal of dairy science》2008,91(9):3424-3438
The objectives of this study were to evaluate the effect of reproductive protocols and reproductive tract score on reproductive performance of dairy heifers and economic outcomes of breeding programs. Holstein heifers (n = 534), 13 ± 1 mo of age, were randomly assigned to 1 of 4 reproductive protocols. On the day of enrollment (d 0), heifers were palpated per rectum and received a score according to the maturity of their reproductive tract (1 = prepubertal; 2 = peripubertal; and 3 = puber-tal). Estrous detection-control heifers (CON, n = 146) received no treatment and were inseminated on detection of estrus for 28 d. Prostaglandin F2α-treated heifers (PGED, n = 137) received 1 injection of PGF2α on d 0 and were inseminated on detection of estrus; heifers not in-seminated by d 14 received a second injection of PGF2α and were observed for estrus and artificial insemination (AI) for an additional 14 d. Heifers enrolled in the estrous detection-timed AI (EDTAI, n = 140) treatment received a controlled internal drug-release (CIDR) insert on d 0, and 7 d later, the CIDR was removed and all heifers received an injection of PGF2α, heifers received AI on detection of estrus, and those not inseminated by 72 h after PGF2α received an injection of GnRH concurrent with AI. Heifers in the GnRH-timed AI (GTAI, n = 111) treatment received 1 injection of GnRH on d 0, on d 6 heifers received a CIDR insert and injections of GnRH and PGF2α, on d 13 the CIDR was removed and heifers received an injection of PGF2α, and 48 h later all heifers received an injection of GnRH and AI. Pregnancy was diagnosed at 32 ± 3 and 62 ± 3 d after AI. Cost of reproductive protocols and their economic outcomes were calculated for a 28 d period beginning at enrollment. Heifers in the PGED treatment were inseminated at a faster rate than CON heifers. A smaller proportion of prepubertal and peripubertal heifers were inseminated within 14 d of enrollment compared with pubertal heifers. Pregnancy per AI of CON and PGED heifers was greater compared with EDTAI and GTAI heifers. Proportion of GTAI heifers pregnant at the end of the 28-d breeding program was or tended to be smaller compared with PGED and CON heifers, respectively. Heifers in the CON and PGED treatments had the smallest cost per pregnancy followed by heifers in the EDTAI and GTAI treatments, respectively. When different scenarios were evaluated, however, the mean cost per pregnancy was smallest for PGED heifers. Cost per pregnancy generated was greatest for prepubertal heifers, whereas pubertal heifers had the smallest cost per pregnancy generated. Treatment of dairy heifers with PGF2α every 14 d until insemination and pregnancy results in the best economic outcomes, and screening heifers according to RTS may prove beneficial to identify heifers that may not be pubertal and would have compromised reproductive and economic performance in a breeding program. 相似文献
57.
Botaro BG Lima YV Aquino AA Fernandes RH Garcia JF Santos MV 《The Journal of dairy research》2008,75(2):176-181
The objective was to evaluate the effect of beta-lactoglobulin (beta-lg) polymorphism and seasonality on milk composition (fat, lactose, total solids, milk urea nitrogen, total protein, true protein, casein and somatic cell counts) of Holstein and Girolando cows. Milk and blood samples from 278 Holsteins cows and 156 Girolando cows were taken during two dry seasons and two rainy seasons, for milk composition analysis and to determine beta-lg genotypes, respectively. BB genotype was the most frequent for both breeds, followed by AA genotype for Holstein (BB>AA>AB) and by AB for Girolando cows (BB>AB>AA). No differences were found in milk compositional characteristics among genetic variants of beta-lg (AA, AB and BB) either between Holstein or Girolando cows. No association between milk composition and beta-lg genetic polymorphism was observed. During the dry season, independently of the breed considered, higher contents of lactose, true protein, casein and casein:true protein ratio were found. 相似文献
58.
Carlos Eduardo de Ara jo Padilha Juliana Chris Silva de Azevedo Francisco Canind de Sousa J nior S rgio Dantas de Oliveira J nior Domingos Fabiano de Santana Souza Jackson Ara jo de Oliveira Gorete Ribeiro de Macedo Everaldo Silvino dos Santos 《中国化学工程学报》2018,26(12):2471-2476
In this study the potential of cloud point extraction formed by a non-ionic surfactant was used in order to separate polyphenols from industrial residues of camu-camu. The effects of operational conditions of the cloud point extraction (CPE) on the polyphenol recovery and volumetric ratio were investigated. The results showed a maximum recovery of 95.71% that was obtained using 7.0 wt% Triton X-114, native pH (3.25), and 80 wt% polyphenol extract at 30 °C. The use of cloud point extraction was successful to recover the polyphenols from agroindustrial residue since it is a simple as well as of low-cost technique. 相似文献
59.
Diego Santos Vieira de Jesus 《材料科学与工程:中英文B版...》2021,(1):16-19
New materials are fundamental to the growth,security,and quality of life of human being sand open doors to technologies in civil,chemical,nuclear,aeronautical,mechanical,biomedical,and electrical engineering.Creative companies use multiple materials in the development of their activities,such as solid stone,fiber glass,concrete,and glass reinforced concrete,for example.Based on bibliographic research,the article examines the synergy between materials science&engineering and creative economy.The main argument indicates that this synergy creates solutions and functionalities that add value to existing products and allow the development of new products with competitive advantages.It may also contribute to the preservation of cultural values and promote sustainability. 相似文献
60.
本文根据美国最近研制、开发的高倾角压带式输送机(HAC)的结构、特点和技术性能,除介绍它在几个深坑露天矿的使用实例外,还着重介绍它在连续装船、卸船、料场堆料和井下提升等各个领域的应用前景。 相似文献